Snort mailing list archives

Re: byte_test/byte_jump negative offsets


From: Nick Randolph <drandolph () sourcefire com>
Date: Mon, 22 Dec 2014 13:50:25 -0500

You want -8. The cursor is at the end of the content match. -4 only moves
the cursor to the beginning of "tEXt".

On Thu, Dec 18, 2014 at 3:11 AM, Praveen D <praveend.hac () gmail com> wrote:

Hi,

Below is the data which I am trying to detect
1c 0c 00 00 *74 45 58 74* 41 41 41 41 41 41 41 41   ....*tEXt*AAAAAAAA

content:"tEXt"; byte_test:4,>,0x3000,*-4*,relative;
Extract 0x1c0c0000 and compare with 0x3000

After matching tEXt, where does the pointer pointed to? Should I use
offset:-4 or offset:-8?

Best Regards,
Praveen Darshanam


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-- 

Nick Randolph
Research Engineer
Sourcefire, Inc.
nrandolph () sourcefire com
Sourcefire.com <http://www.sourcefire.com/>
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